GB2040303A

GB2040303A - Chromogenic composition

Info

Publication number: GB2040303A
Application number: GB7943389A
Authority: GB
Original assignee: Appleton Papers Inc
Current assignee: Appvion Operations Inc
Priority date: 1978-12-29
Filing date: 1979-12-17
Publication date: 1980-08-28
Also published as: DE2952409A1; SE7910523L; AU5415079A; CH644551A5; NZ192451A; DD150261A5; FI71693B; DK536479A; NL7909139A; IT1209170B; FR2445360A1; ES8100166A1; US4275905A; PL125743B1; GB2082194B; IE49345B1; CA1141541A; ES488799A0; AU535642B2; IE792517L

Description

1 GB 2 040 303 A 1

SPECIFICATION

Chromogenic composition This invention relates to a chromogenic composition a process for its preparation, a microencapsulated 5 chromogenic composition, and pressure-sensitive record material containing the composition.

The colour forming systems used in pressure-sensitive record material generally employ a substantially colourless chromogenic material, a colour developer capable of reacting with the chromogenic material to generate a colour and a solvent in which the colour forming reaction can take place. The reactive components of the colour forming system are kept apart until the time of use and this is normally achieved 10 by microencapsulating a chromogenic composition comprising a solvent solution of the chromogenic material. At the time of use, the application of pressure causes rupture of those microcapsules that are subjectto such pressure and consequential release of the chromogenic solution. This then allows both colour forming components to be brought into reactive contact and to generate a coloured image which exactly corresponds to the pattern of applied pressure. In this way, pressure-sensitive record material can be 15 used to provide copies without the need for any carbon paper. In a self- contained record system, the record matrial comprises a sheet having a coating of the microencapsulated chromogenic solution in admixture with the colour developer. Alternatively, the microencapsulated chromogenic solution and the colour developer may be dispersed within the sheet itself.

In a transfer record system, at leasttwo record materials are employed. One comprises a sheet having a 20 coating of microencapsulated chromogenic solution (the CB sheet) and the other comprises a sheet having a coating of a colour developer (the CF sheet). The sheets are assembled together as a manifold set with their coatings in contiguous relationship so that transfer of the chromogenic solution can take place from the CB sheetto the CF sheet. To provide further copies, the manifold set may additionally include a third record material which comprises a sheet having on one side a coating of the microencapsulated chromogenic solution and on the other side a coating of the colour developer. One or more of these sheets (CF13 sheets) are disposed between the CF and the CB sheets in the manifold set with each micrcapsule coating in contiguous relationship with a colour developer coating.

Whether a self-contained or a transfer record system is used, one of the important properties of the microencapsulated chromogenic solution is its reactivity, i.e. its ability to produce an image of acceptable 30 intensity on reaction with a colour developer. Generally, most record materials that contain a microencapsu lated chromogenic solution show a satisfactory reactivity if they have not been exposed to ambient conditions, including, in particular, light, However, after prolonged exposure to such conditions, the record materials invariably have a much poorer reactivity. This reduction in reactivity, which is often referred to as CB decline, can moreover be greater if certain solvents or chromogenic materials are used. For example, a 35 chromogenic solution of Crystal Violet Lactone in 2,2,4-trimethyl 1,3- pentanediol di-i-butyrate (TXIB) suffers particularly from the problem of CB decline.

It is an object of the present invention to provide a chromogenic composition suitable for use in pressure-sensitive record systems and which does not suffer, at least not to the same extent, from the above-mentioned problem with CB decline.

In a first aspect, the present invention provides a chromogenic composition which comprises a substantially colourless chromogenic material, an organic solvent for the chromogenic material, and pyridyl blue andior a phenol having having a free reactive position. In a second aspect, the present invention provides a process for preparing a chromogenic composition which comprises admixing a substantially colourless chromogenic material, an organic solvent for the chromogenic material and pyridyl blueand/ora 45 phenol having a free reactive position.

The use of pyridyl blue or a phenol having a free reactive position imparts to the chromogenic composition an ability to resist CB decline. In addition, coloured images produced from the composition have excellent fade resistance and hue stability.

Pyridyl blue itself is novel and has the following formula:- HS 0C2 H S N 0 C- C2H5 0 1 = CH3 C2H5 U L 0 and/or C2H5 0C2H5 0 0 E 17@s ' ? C2H5 N 0 N, 0 C=0 CH3 \ú2H5 60 5-(1-Ethy]-2-methylindol- 7-(1 -Ethyl-2-m ethyl i ndo I 3-yl)-5- (4-diethylamino- 3-yi)-7-(4-diethylamino 2-ethoxyphenyl)-5,7-dihydro- 2-ethoxyphenyl)-5,7 furo(3,4-b) pyridin-7-one dihydrofuro(3,4-b)pyridin 5-one 65 2 GB 2 040 303 A Either of these two isomers can be used in the chromogenic composition although the pyridin-5-one isomer is the more effective. However, the processes which can be used to synthesise pyridyl blue (for example see British patent 1367567 and U.S. patent 3775424) usually produce a mixture of isomers and separation of one isomer from the mixture by conventional techniques (e.g. chromatography) is difficult, time-consuming, and costly on a com.Tercial basis. It is therefore more convenientto use a mixture and to use for its preparation a synthetic process in which the conditions have been selected to favourformation of the pyridin-5-one isomer. In this way, a mixture can be obtained for use in the chromogenic composition and in which the more effective pyridin-5-one isomer predominates.

The amount of pyridyl blue employed in the chromogenic composition should of course be sufficient to achieve the desired effect and is preferably between 0.6 to 3 weight percent (i.e. parts by weight of pyridyl blue per 100 parts by weight of solvent).

A phenol having a free reactive position includes those which have a free ortho-or para-position. Such phenols are normally substituted by any of a straight or branched alkyl group, an aralkyl group, or an aralkenyl group. Specific examples include dodecylphenol; p-1,1,3,3- tetramethylbutyl phenol; 2,4-di-t butylphenol; p-cumylphenol; and styrenated phenol. These phenols are known and can by prepared by conventional processes.

The phenol is preferably used in an amount of from 1 to 7jor example 2 to 5, weight per cent (i.e. parts by weight of phenol per 100 parts of chromogenic composition).

To achieve an even more substantial resistance to CB decline, it is preferred that both pyridyl blue and a phenol having a free reactive position are used in the chromogenic composition.

A substantially colourless chromogenic mateial of use in the present invention includes one or more of 3,7-bis (dimethylamino)-10-benzoyi-phenothiazine (benzoyl leuco methylene blue, BLMB); 3,3-bis (dimethy ]amino phenyl)-6- dimethylaminophthalide (Crystal Violet Lactone, CVQ; 2'- anilino-6'-diethyiamino-3' methylfluoran (N102); 3,21-bis (1 -ethyl-2-m ethyl i ndo 1-3-y1) phthalide (indolyl red); 3,3-bis (1-butyl-2 methyl i ndol-3-VI) phthalide; spiro-7-chloro-2,6-dimethyi-3- ethylaminoxanthene-9,2-(2H) naphthol (1,8-bc) furan; 7-chloro-6-methyi-3-diethylaminofluoran; 3-diethylaminobenzo (b) fluoran; 3-(4-diethylamino-2 ethoy)-3-(2-m ethyM -ethyl i ndo 1-3-yi) phthalide; 3-(4-diethyl am i no- 2-butoxy)-3-(2-m ethyM -ethyl indo 1-3-y1) phthalide; and 3,7-bis (diethylamino)-1 0-benzoyi-benzocazine.

In addition pyridyl blue itself can be used as the chromogenic material as it generates a blue colour on reaction with a colour developer. Such chromogenic material would inherently provide resistance to CB decline and thus the combination pf pyridyl blue with a solvent therefore is included within the scope of the chromogenic composition of the invention. However, it is preferred to use pyridyl blue with other dyes in order that the desired hue or colourtone can be achieved and to use it as a partial replacement of Crystal Violet Lactone in existing chromogenic compositions. A particularly useful chromogenic material comprises BLMB (up to 1.3 weight per cent), CV1- (up to 3 weight per cent), indolyl red (up to 2 weight per cent), and N102 (up to 3 weight per cent) together with pyridyl blue (0.6 to 3 weight per cent).

Examples of a suitable organic solvent for the chromogenic material include dialkyl phthalates in which the alkyl groups have from 4 to 13 carbon atoms, such as dibutyl, diocty], dinonyi and ditridecyl phthalates; 2,2,4-tri methyl -1,3-penta n ed io 1 di-i-butyrate (TXIB, U.S. patent 4027065); ethyidiphenyl methane (U.S. patent 3996405); alkyl biphenyls, such as mono-i-propylbiphenyl (U.S.patent 3627581); C10-C14 alkyl benzenes, such 40 as dodecyl benzene; diaryl ethers, such as diphenyl ether, di(aralkyl) ether, such as dibenzyl ether, and aryl aralkyl ethers, such as phenyl benzyi ether; liquid dialkyl ethers having at least eight carbon atoms; liquid alkyl ketones having at least nine carbon atoms; alkyl or aralkyl benzoates, such as benzyl benzoate; alkylated naphthalenes; and partially hydrogenated terphenyls. Preferred solvents include ethyidipheny 45]methane and 2,2,4-trimethyi-1,3-pentanediol di-i-butyrate.

These solvents, which are all substantially odourless, may be used alone or in combination. They may also be used with a diluent in order to reduce the cost of the chromogenic composition. Of course, the diluent must not be chemically reactive with either the solvent or any other component of the composition and must be at least partially miscible with the solvent so as to give a single phase. The diluent is used in an amount sufficient to achieve a cost benefit but without impairing the solubility of the chromogenic material. Diluents 50 are already known in the art and a preferred example thereof is Magnaflux oil, which is a mixture of saturated aliphatic hydrocarbon oils having a distillation temperature of 320 to 550'F.

The present invention also provides a microencapsulated chromogenic composition, as hereinbefore defined. Microencapsulation of the composition can be carried out by processes known in the art, for example, by using gelatin as described in U.S. patents 2800457 and 3041289, by using an urea-formaldehyde 55 resin as disclosed in U.S. patents 4001140,4087376 and 4089802, and by using various melamineformal dehyde resins as disclosed in U.S. patent 4100103.

Colour developers suitable for use with the composition of the present invention are known in the art, and include oil-soluble metal salts of phenol-formaldehyde novolak resins of the type described in U.S. patents 3672935,3732120 and 3737410. A preferred example of a suitable resin is a zinc-modified, oil-soluble phenol-formaldehyde resin, such as the zinc salt of a p-octylphenol- formaidehyde resin orthe zinc salt of a p-phenylphenol formaldehyde resin.

The present invention also provides pressure-sensitive record material which contains a chromogenic composition, as hereinbefore defined.

Coating formulations and processes for the preparation of pressuresensitive record material are generally 65 2 1 z 3 GB 2 040 303 A 3 known in the art, for example U.S. patents 3 627 581, 3 775 424 and 3 853 869.

The present invention will now be described with reference to a number of examples thereof, in which all parts are by weight.

Example 1 -Preparation ofpyridyl blue Quinolinic anhydride (0.21 mol) and 1-ethyi-2-methyi-indole (0.33 mol) were mixed together in a reaction flask at 65-70'Cfor 3 hours. The reaction mixture was then cooled and washed with benzene (or chlorobenzene) to provide (1-ethyi-2-methylindol-3-yi) (3-carboxypyridin- 2-yi) ketone and its isomer (0.19 mol).

(1-Ethyi-2-m ethyl indo 1-3-y1) Q-carboxypyridi n-2-yO ketone and its isomer (together 58.0g; 0.188 mol) were 10 stirred for two hours at 60-65'C with N, N-diethyl-m-phenetidine (35.3g; 0.188 mol) and acetic anhydride (250mi). The reaction mixture was poured into water (500mi) and the acetic anhydride hydrolyzed by slowly adding 29% ammonium hydroxide (450m1). After stirring for two hours, the resulting solid was filtered and washed with water, 40% methanollwater (200mi) and petroleum ether (b.p. 60-11 O'C; 50mi). The solid was then dried to constant weight in an oven at 75'C to give a mixture (91 respectively) of 7-(l-ethyl-2 methyl i ndol-3-y])-7-(4-d iethyla m ino-2-ethoxy-phenyi)-5, 7-di hyd rofu ro (3,4-b) pyridin-5-one and 5-(1-ethyi-2 methyl-indol-3-yi)-5(4-diethylamino-2-ethoxyphenyi)-5,7-dihydrofuro (3, 4-b) pyridin-7- one (80.5g, 90%, m.p.-134.137'C).

Example 2 - Preparation of chromogenic compositions A number of chromogenic solutions were prepared by admixing the following components in the parts indicated:- TABLE 1

1 2 CV1- 3.4 3.4 3.4 4 5 6 7 8 3.4 3.4 3.4 3.4 3.4 Indolyl Red 1.1 1.1 1.1 --- --- --- 1.2 1.2 30 N-1 02 1.1 1.1 1.1 1.2 1.2 1.2 1.2 1.2 Other chromogenic 35 material --- --- --- 1.2 (a) 1.2 (b) 1.2 (c) --- --Alkylate 215 126.4 126.4 126.4 130.0 130.0 130.0 130.0 130.0 40 Ethyidiphenyl methane 68.0 68.0 68.0 60.0 60.0 60.0 60.0 70.0 Dodecyl; 45 phenol 10.0 4.0 10.0 10.0 10.0 10.0 ClTC15 alkylbenzene (a) spiro-7-chloro-2,6-dimethyl-3-ethylaminoxanthene- 9,2-(2H) naphtho (1,8-bc)furan. (b) 3-diethylaminobenzo(b) fluoran.

(c) 7-ch loro-6-m ethyl-3-di ethyl am in ofluoran.

--- 45 4 GB 2 040 303 A 4 TABLE 2

9 10 11 Pyridyl Blue --- 0.6 1.2 CV1- 3.4 3.4 2.8 12 Indolyl Red 1.1 1.2 1.2 13 1.8 2.4 --- 1.2 1.2 2.2 1.2 14 1.6 1.2 3.4 1.1 14 16 2.8 2.8 1.2 1.2 N-102 1.1 --- --- --- --- 1.1 0.6 -- Alkylate 215 130.0 130.0 130.0 130.0 130.0 130.0 130.0 200.0 15 Ethyidi phenyime thane 70.0 70.0 70.0 70.0 70.0 70.0 70.0 --- Example 3 - Preparation of microencapsulated chromogenic compositions Each of the chromogenic solutions 1 to 16 was microencapsulated according to the procedure disclosed in U.S. patent 4001140. Briefly, this was as follows:

parts of the chromogenic solution was emulsified in a mixture of 35 parts of 10% EMA 31 (ethylene-maleic anhydride copolymer with a molecular weight range of 75, 000 to 90,000, supplied by 25 Monsanto Chemical Co.) in water, 32 parts of 20% EMA 1103 (ethyl ene-ma 1 eic anhydride copolymer with a molecular weight range of 5000 to 7000, supplied by MONSANTO Chemical Co. ) in water, 133 parts of water, parts of urea and 1 part of resorcinol, adjusted to pH 3.5. Following emulsification, 29 parts of 37% formtildehyde was added and the mixture was placed in a 55'C water bath with stirring. Aftertwo hours, the temperature of the water bath was allowed to equilibrate with the ambient temperature while stirring was 30 maintained.

Example 4 -Preparation of microcapsule coating formulations Each of the microcapsule batches 1 to 16 was made up into a coating formulation using the materials and parts listed below:

Parts Wet Parts Dry Capsule batch 80 40 Wheat Starch Granules 10 10 40 Penford 230, 10% 40 4 Water 100 Etherified corn starch binder made by Penick and Ford Ltd.

Example 5 - Preparation of CB record materials Each of the coating formulations 1 to 16 were dispersed, applied to a paper base and drawn with a No. 12 wire-round coating rod and the coatings dried with a heat gun.

Example 6-CB decline comparative tests Each of the CB record materials 1 to 16 were subjected to the Typewriter Intensity (T1) Test in which a standard pattern is typd on a manifold set comprising a CF and a CB sheet, (the CF sheet in the present tests being coated with a zinc-modified phenolic resin as disclosed in U.S. patents 3732120 and 3737410). A coloured print image corresponding to the pattern is thus produced on the C17 sheet and the intensity of the image is determined with the aid of an opacimeter.

The intensity is a measure of colour development and is the ratio of the reiectance of the print image to that of the unimaged area (I/[o) expressed as a percentage. A high value indicates little colour development and a low value indicates high colour development.

Typewriter Intensity (T1) Tests were conducted before exposure of the CB sheet to fluorescent light 60 irradiation and after one and two hours exposure of the CB sheet to such irradiation. In all cases, the intensity measurements were taken at 20 minutes after imaging.

The device for the fluorescent light tests comprised a light box containing a bank of 18 daylight fluoroscent lamp (21 inches (53.3cm) long, 13 nominal lamp watts) vertically mounted on 1 inch central supports. The CB sheets were placed 1 to 1.5 inches (2.5 to 3.8 cm) from the lamps.

GB 2 040 303 A 5 The results obtained for the sixteen CB record materials are presented below:

CB Record Initial Change in T1 after Light Material No. TI Exposure of CB Coatings 5 1 Hr. 2 Hr.

Exposure Exposure 1 41 -2 -6 10 2 43 -3 -7 3 36 -13 -34 4 41 -6 -15 15 38 -5 -13 6 38 -8 -15 20 7 38 -5 -10 8 35 -18 -32 9 44 -20 -33 25 41 -17 -29 11 48 -12 -24 30 12 41 -12 -20 13 47 -12 -19 14 35 -15 -31 35 44 -14 -24 16 46 -14 -24 40 The amount of CB decline which is acceptable is of course dependent upon the duration of light exposure of the C13.

For a 2 hour exposure a loss of more than about 26 units is unacceptably high. Thus, record materials 1, 2, 4,5,6 and 7 which contained dodecylphenol and record materials 11, 12,13, 15 and 16 which contained a sufficient amount of Pyridyl Blue produced a sufficiently low amount of CB decline to be acceptable. Record 45 materials 3,8, 9 and 14 which were controls containing no material added to provide CB decline resistance and record material 10 which had an insufficiently low amount of Pyridyl Blue all showed an unacceptably high amount of CB decline.

Example 7- Preparation of chromogenic compositions Additional chromogenic solutions were prepared by admixing the following components in the parts indicated:

Pyridyl blue 2.0 55 CV1- 2.0 Indolyl red 1.2 AI kyl ate 215 182.0 60 Ethyl di phenyl methane 6.0 Di-n-hexyl ketone 6.0 6 GB 2 040 303 A 6 In addition, each of the solutions contained 6.0 parts of one of the following phenols:

17 octyl phenol 18 dodecylphenol 5 19 21 22 23 cumyi phenol styrenated phenol 4,4-methylene-bis(2-tertbutyl-6-methyI phenol) 2,4,6-tri-tertbutyl phenol 2, 6-di-tertbutyl phenol Example 8- Preparation of microencapsulated chromogenic composition Each of the chromogenic solutions 17 to 23 was microencapsulated according to the procedure disclosed in the U.S. patent 4100103. The specific procedure was as follows:

parts of the chromogenic solution eas emulsified in a mixture of 35 parts of 10% EMA 31 in water and parts of water, adjusted to pH 3.7.

A mixture of 32 parts of 20% EMA 1103 and 30 parts of water was adjusted to pH 4.0 and 30 parts of Resimene 714 (methylated methylol melamine resin produced by Monsanto Chemical Co.) was added thereto. This mixture was added to the emulsion and the total mixture was placed in a 550C. water bath with 25 stirring. After two hours, the temperature of the water bath was allowed to equilibrate with the ambient temperature while stirring was maintained.

Example 9 -Preparation of CB record materials 30 Each of the microcapsule batches 17 to 23 was made up into a coating formulation using the materials and 30 procedure of example 4. Each of the coating formulations 17 to 23 were coated on a paper base as described in example 5.

Example 10 - CB decline comparative tests The CB record materials 17 to 23 were subjected to the same tests in the same manner as described in 35 example 6.

The results obtained are presented below:

CB Record Initial Change in TI after Light Material No. TI Exposure of CB Coatings 40 1 Hr. 2 Hr.

Exposure Exposure 17 41 -2 -7 45 18 42 -4 -7 19 42 -5 -11 50 so 20 36 -7 -14 21 38 -23 -34 5522 39 -20 -27 55 23 40 -3 -13 Using the guidelines of acceptability set out in example 6, record materials 17,18,19,20 and 23 are all clearly satisfactory. The record materials 21 and 22 contained a phenol with no reactive position and are 60 clearly are unsatisfactory.

7 GB 2 040 303 A 7 Example 11 - Preparation of chromogenic compositions Further chromogenic solutions were prepared by admixing the following components in the parts indicated:

24 25 26 27 28 29 5 Pyridyl Blue 2.0 2.0 --- 2.0 2.0 2.0 CV1- 2.0 2.0 3.4 2.0 2.0 2.0 10 Indolyl Red 1.2 1.2 1.1 1.2 1.2 1.2 N-102 --- --- 1.1 ---- --- Other Chromogenic 15 material --- 1.0(d) --- --- 1.,0(e) -- AI kyl ate 215 200.0 200.0 130.0 190.0 180.0 180.0 ethyidiphenyi 20 methane ----- 70.0 --- -- dodecylphenol --- --- 10.0 --- 10.0 Other additives ----- --- 20.0(f) 10.0(g) 25 (d) 3,7-bis(diethylamino)-10-benzoyibenzoxazine (e) BLMB (f) methyl nonyl ketone (9) methyimyristate Example 12 Preparation of CB record materials Each of the chromogenic solutions 24 to 29 was microencapsulated according to the procedure of example 3.

Each of the microcapsule batches 24 to 29 was made up into a coating formulation using the materials and 35 procedure of example 4.

Each of the coating formulations 24 to 29 was coated on a paper base as described in example 5.

Example 13 - CB decline comparative tests The CB record materials 24 to 29 were subjected to the same tests in the same manner as described in 40 example 6.

The results obtained are presented below:

CB Record Initial Change in T1 after Light Material No. Tl Exposure of CB Coatings 45 1 Hr. 2 Hr.

Exposure Exposure 24 43 -8 -13 50 43 -8 -14 26 39 -13 -34 55 27 47 0 3 28 39 -5 -11 29 46 -4 -6 60 Record materials 24,25 and 28, which contain Pyridyl Blue, all showvery good CB decline resistance. Record materials 27 and 29 which contain both Pyridyl Blue and dodecyl phenol show excellent CB decline resistance. Record material 26 is a control containing no material for resisting CB decline and is unsatisfactory.

8 GB 2 040 303 A 8 Example 14 -Preparation of chromogenic compositions A final number of chromogenic solutions were prepared by admixing the following components in the parts indicated:

30 31 32 5 Pyridyl Blue 91.8 91.8 -- CV1- 21.6 21.6 91.8 10 Indolyl Red 27.0 27.0 14.8 N- 102 16.2 16.2 29.7 2,3,4-trimethyi- 15 1,3-pentanediol diisobutyrate 3495.6 --- 3509.1 Magnaflux Oil 1747.8 3146.0 1754.6 20 Dibutyl Phthalate --- 2097.4 --- Example 15 - Preparation of microencapsulated chromogenic composition Each of the chromogenic solutions 30 to 32 was microencapsulated according to a procedure similar to that of example 8. The specific procedure was as follows:

5400 parts of a chromogenic solution was emulsified in a mixture of 1000 parts of 10% EMA 31 in water and 5600 parts of water, adjusted to pH 3.7.

The pH of the emulsion was then adjusted to 4.0. A mixture of 1000 parts of 10% EMA 1103 in water adjusted to pH 4.0, 1000 parts of water and 1000 parts of Resimene 714 was added to the emulsion. The resulting mixture was heated to 55'C. for 2 hours. After that time the temperature of the mixture was allowed 30 to equilibrate with the ambient temperature while stirring was maintained.

Example 16 - Preparation of microcapsule coating formulations Each of the microcapsule batches 30 to 32 was made up in to a coating formulation using the materials and parts listed below:

Q Parts Dry Capsule batch 70.40 40 Wheat Starch Granules 21.10 Etherified Corn Starch Binder 4.25 Poly(vinyl alcohol)Binder 4.25 45 Sufficient water was added to produce a 17.4% solids formulation for coating.

Example 17 - preparation of CB record materials 50 Each of the coating formulations 30 to 32 were dispersed and coated on a paper base using a pilot plant air 50 knife coater, and then dried. Example 18 - CB decline comparative tests The CB record materials 30 to 32 were subjected to the same tests in the same manner as described in 55 example 6.

9 The results obtained are presented below:

GB 2 040 303 A 9 CB Record Initial Change in TI after Light Material No. TI Exposure of CB Coatings 1 Hr. 2 Hr.

Exposure Exposure 46 -2 -9 10 31 47 -1 -3 32 53 -17 -30 Using the guideline of acceptability set out in example 6, record materials 20 and 21, containing Pyridyl 15 Blue, show excellent resistance to CB decline while the control with no Pyridyl Blue, record material 32, produced unsatisfactory results.

Claims

1. Achromogenic composition which comprises a substantially colourless chromogenic material, an organic solvent for the chromogenic material, and pyridyl blue, which is 5-(1-ethyi-2-methylindol-3-yi)-5(4diethylamino-2-ethoxyphenyl)-5,7-dihydrofuro (3,4-b) pyridin-7-one and/or 7-(1 -ethyl-2-methylindol-3-yl)-7(4-diethylamino-2-ethoxyphenyi)-5, 7-dihydrofuro (3,4-b) pyridin-5-orle, andlor a phenol having a free reactive position.

2. Achromogenic composition according to claim 1, wherein pyridyl blue is 7-(1-ethyi-2-methylindol-3yl)-7-(4-diethylamino-2-ethoxyphenyl)-5,7dihydrof uro (3,4-b) pyridin-5-one.

3. Achromogenic composition according to claim 1, wherein pyridyl blue is a mixture of 5-(l-ethyl-2methyl i ndol-3-yl)-5-(4-d iethyl am i no-2ethoxyphenyi)-5, 7-d i hydrofu ro (3,4-b) pyridin-7-one and 7-(1-ethy]-2methylindol-3-yi)-7-(4-diethylamino-2-ethoxyphenyl)-5,7-dihydrofuro (3,46) pyridin-5-one.

4. A chromogenic composition according to anyone of the precedig claims, wherein the phenol has a free ortho-or para-position.

6. A eh romogenic composition according to claim 4, wherein the phenol is dodecyl phenol, p-1, 1, 3, 3-tetra methyl butyl p hen ol, 2, 4-di-t-butyl phenol, p-cumylphenol, or styrenated phenol.

6. A chromogenic composition according to either of claims 4 and 5, wherein the phenol is used in an 35 amount of from 1 to 7 weight percent.

7. A chromogenic composition according to claim 6, wherein from 2 to 5 weight percent is used.

8. A chromogenic composition according to anyone of the preceding claims, wherein both pyridyl blue and a phenol having a free reactive position are used.

9. Achromogenic composition according to anyone of the preceding claims, wherein the chromogenic 40 material includes 3,3-bis (dimethylaminophenyl)-6-dimethylaminophthalide, 3,3-bis (1 -ethyl-2-m ethyl i ndol 3-yl) phthalide, and 2'-anilino-6'-diethylamino-3'-methyifiuoran.

10. A chromogenic composition according to anyone of the preceding claims, wherein the organic solvent is ethyidiphenyl methane or 2,2,4-trimethyl-1,3-pentanediol di-i- butyrate.

11. A process for preparing a chromogenic composition, as defined in anyone of claims 1 to 10, which 45 comprises admixing a substantially colourless chromogenic material, an organic solvent for the chromogenic material, and pyridyi blue, which is 5-(1-ethyl-2-methylindol3-yl)-5-(4-diethylamino-2- eth oxyph enyl)-5,7-di hyd rofu ro (3, 4-b) pyridi n-7-one a nd/o r 7-(1 - ethyl -2-m ethyl i ndo 1-3-yl)-7-(4-d i ethyla mi no 2-ethoxyphenyi)-5,7-dihydrofuro (3,4-b) pyridin-5-one, and/or a phenol having a free reactive position.

12. A microencapsulated chromogenic composition in which the chromogenic composition is as defined 50 in any one of claims 1 to 10.

13. Pressure-sensitive record material which contains a chromogenic composition as defined in anyone of claims 1 to 10, and 12.

14. A chromogenic composition substantially as described hereinbefore with reference to anyone of exampes 2, 11 and 14.

15. A process for preparing a chromogenic composition substantially as described hereinbefore with reference to anyone of the examples 2,7, 11 and 14.

16. A microencapsulated chromogenic composition substantially as described hereinbefore with reference to anyone of the examples 3,8,12 and 15.

17. Pressure-sensitive record material substantially as described hereinbefore with reference to anyone 60 of examples 5,9,12 and 17.

Printed for Her Majesty's Stationery Office, by Croydon Printing Company Limited, Croydon Surrey, 1980. Published by the Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.